Three new diterpene glycosides, virescenosides O (1), P (2), and Q (3), have been isolated from a marine strain of Acremonium striatisporum KMM 4401 associated with the holothurian Eupentacta fraudatrix. Their structures were determined on the basis of HRMALDIMS and NMR data as beta-D-altropyranosido-19-isopimara-8(14),15-diene-7alpha,3beta-diol (1), beta-D-altropyranosido-19-7-oxoisopimara-8(9),15-diene-3beta-ol (2), and beta-D-mannopyranosido-19-isopimara-7,15-diene-3beta-ol (3). The cytotoxic activity of the virescenosides was examined.